High infrared reflection coatings

Abstract

The invention provides low-emissivity coatings that are highly reflective of infrared radiation. The coating includes three infrared-reflection film regions, which may each comprise silver.

What is claimed is: 
     
       1. A coated transparent pane having opposed first and second major surfaces, said coated pane being part of a multiple-pane insulating glazing unit that includes a second pane, wherein the insulating glazing unit has a between-pane space to which the second major surface of said coated pane is exposed, said second major surface bearing a low-emissivity coating that includes the following film regions in sequence moving away from said second major surface: a first transparent dielectric film region, a first infrared-reflection film region, a second transparent dielectric film region, a second infrared-reflection film region, a third transparent dielectric film region, a third infrared-reflection film region, and a fourth transparent dielectric film region, the coating having both a sheet resistance of less than 2.5 Ω/square and an emissivity of less than 0.03, said three infrared-reflection film regions having a combined thickness of greater than 425 angstroms, the coating having a primary dielectric-region ratio that is greater than 0.34 and less than 0.75, the primary dielectric-region ratio being defined as the thickness of the first transparent dielectric film region divided by the thickness of the fourth transparent dielectric film region. 
     
     
       2. The coated pane of  claim 1  wherein the primary dielectric-region ratio is greater than 0.34 and less than 0.6. 
     
     
       3. The coated pane of  claim 1  wherein the emissivity is less than 0.025. 
     
     
       4. The coated pane of  claim 1  wherein the sheet resistance is less than 2.0 Ω/square. 
     
     
       5. The coated pane of  claim 1  wherein the combined thickness of the first, second, and third infrared-reflection film regions is greater than 450 angstroms. 
     
     
       6. The coated pane of  claim 1  wherein the low-emissivity coating includes transparent dielectric film between said second major surface and the first infrared-reflection film region, and wherein between the first infrared-reflection film region and said second major surface the coating has less than 190 angstroms of transparent dielectric film having a refractive index of 1.7 or greater. 
     
     
       7. The coated pane of  claim 6  wherein between the first infrared-reflection film region and said second major surface the coating has less than 175 angstroms of transparent dielectric film having a refractive index of 1.7 or greater. 
     
     
       8. The coated pane of  claim 1  wherein the low-emissivity coating has a total thickness of greater than 1,800 angstroms. 
     
     
       9. The coated pane of  claim 1  wherein the low-emissivity coating has a total thickness of greater than 1,900 angstroms. 
     
     
       10. The coated pane of  claim 1  wherein the low-emissivity coating includes at least one nitride or oxynitride film having a thickness of less than 150 angstroms, and wherein the coating further includes at least one nitride or oxynitride film having a thickness of greater than 50 angstroms. 
     
     
       11. The coated pane of  claim 10  wherein said nitride or oxynitride film having a thickness of greater than 50 angstroms is a spacer layer positioned between two of said infrared-reflection film regions. 
     
     
       12. The coated pane of  claim 1  wherein the coated pane has a major dimension of at least one meter. 
     
     
       13. The coated pane of  claim 1  wherein the emissivity is less than 0.023. 
     
     
       14. The coated pane of  claim 1  wherein both panes of said glazing unit are clear glass. 
     
     
       15. The coated pane of  claim 1  wherein at least one of the infrared-reflection film regions has a thickness of greater than 175 angstroms. 
     
     
       16. The coated pane of  claim 1  wherein at least one of the infrared-reflection film regions has a thickness of greater than 200 angstroms. 
     
     
       17. The coated pane of  claim 7  wherein between the first infrared-reflection film region and said second major surface the coating has less than 140 angstroms of transparent dielectric film having a refractive index of 1.7 or greater. 
     
     
       18. The coated pane of  claim 1  wherein said second major surface is a #2 surface of said glazing unit. 
     
     
       19. The coated pane of  claim 1  wherein the low-emissivity coating has a total thickness of greater than 2,000 angstroms. 
     
     
       20. The coated pane of  claim 1  wherein the coated pane has a transmittance at 740 nm of less than 0.05.